Field of the Invention
The present invention relates to an image forming apparatus and a computer-readable recording medium storing a program.
Description of the Related Art
In an image forming apparatus, for example, an image forming apparatus using an electro-photographic technique (electro-photographic type image forming apparatus), there is a case where periodic density non-uniformity of an image (in the following, called “periodic non-uniformity”) is caused in the sub-scan direction (sheet conveyance direction) perpendicular to the main scan direction. This is caused by non-uniformity in a rotation period of a rotary component such as a photoreceptor drum and a development sleeve used in an image generation process.
A technique of detecting the phase in a sub-module of the rotary component causing the periodic non-uniformity, and performing density correction in synchronization with the phase, is known as a technique of correcting the above periodic non-uniformity (refer to Patent Literature 1, for example). The conventional technique is configured to measure a pattern having a uniform gradation in the sub-scan direction, detect currently caused periodic non-uniformity from the measurement result, and generate a correction value from the detection result to apply the correction value to density correction.